Process for the production of hexaammine cobalt nitrate

Abstract

A novel process for producing bexaammine cobalt(III) nitrate from a cobalt(II) salt is disclosed. The product is useful in formulating gas generant compositions.

What we claim is: 
     
       1. A process of making hexaammine cobalt (III) salt comprising the steps of: (a) providing a solution of Co(X) 2  and NH 4  X, wherein X is at least one selected from the group consisting of chloride, bromide, perchlorate, and nitrate;   (b) combining the solution from (a) with an ammonia source comprising ammonium hydroxide, an ammonia-containing gas or a combination thereof;   (c) aging the combination obtained in (b) to provide a final hexaammine cobalt (III) salt with a particle size of between about 25 and about 45 microns;   (d) adding a surface active catalyst to the aged combination in (c);   (e) introducing an oxygen-containing gaseous oxidizer to the aged combination in (d) to form a reaction mixture;   (f) maintaining the temperature of the reaction mixture in the range of 30° C. to 50° C.; and   (g) cooling the mixture from (f) and recovering said hexaammine cobalt (III) salt therefrom as an admixture with the surface active catalyst.   
     
     
       2. The process according to claim 1, wherein X is nitrate. 
     
     
       3. The process according to claim 2, wherein the solution in step (a) is formulated from constituents comprising water, ammonium nitrate and Co(NO 3 ) 2 . 
     
     
       4. The process according to claim 2, wherein said process the hexaammine cobalt(III) nitrate salt (HACN) is the hexaammine cobalt(III) salt, and HACN is recovered by filtration and cobalt is recovered from the obtained filtrate; Co(NO 3 ) 2  is prepared using the recovered cobalt; and the thus prepared Co(NO 3 ) 2  is recycled to prepare a solution for use in step (a). 
     
     
       5. The process according to claim 1, wherein the oxygen-containing gaseous oxidizer comprises oxygen gas, nitrogen-oxygen gas mixtures, air or mixtures thereof. 
     
     
       6. The process according to claim 1, wherein aging in step (b) is conducted for 24 hours. 
     
     
       7. The process according to claim 1, wherein the aging in step (b) is conducted at a temperature from 20° C. to 35° C. 
     
     
       8. The process according to claim 2, wherein the concentration of NH 4  NO 3  is from about 1.5 mols to about 3.0 mols per mol of cobalt. 
     
     
       9. The process according to claim 1, wherein the surface active catalyst comprises activated carbon. 
     
     
       10. The process according to claim 1, 2, 8 or 9, wherein (0.8 wt. % to 1.5 wt. % of the) surface active catalyst is used, in relation to the theoretical yield of recovered HACN. 
     
     
       11. The process according to claim 1, wherein said process includes the further step of formulating a gas generant composition using the recovered hexaammine cobalt(III) salt. 
     
     
       12. The process according to claim 2, wherein said process includes the further step of formulating a HACN-containing gas generant composition using the recovered HACN. 
     
     
       13. The process according to claim 1, wherein said process includes the further step of purifying said hexaammine cobalt (III) salt by recrystallization from water.